Introduction High altitude air cooling has always been somewhat of a mystery to the uninformed. The first reaction to the situation is that there is just not enough air at altitudes greater than six kilometers (20,000 ft). At times this may be true, but many things can be done to improve the cooling and obtain an acceptable design. The most important thing to remember when … [Read more...]
Convection and radiation heat loss from a printed circuit board
In last issue's column, a method for calculating the thermal conductivity of a printed circuit board (PCB) was described. Now, we look at a more complicated heat transfer process, namely the loss of heat from the surface of a PCB to the ambient air. This situation is more challenging to describe mathematically since it involves the simultaneous processes of heat spreading by … [Read more...]
Thermal testing and control by means of built-in temperature sensors
Introduction This paper will discuss a new approach to the measurement of the thermal properties of PCBs and the packages mounted to them. It is intended to replace traditional solutions, such as using thermocouples and data acquisition equipment. The basic idea of this approach is that the IC chips themselves will be used to measure and acquire temperature data. It will be … [Read more...]
Pressure drop coefficients for thin perforated plates
Almost everyone working on pressure drop coefficients of perforated plates encounters the work of I.E. Idelchick {1}. A plethora of graphs or equations - some of which are impossible to evaluate quickly - must then be addressed. To simplify this issue for the reader, this month's Technical Data page has been designed to provide an overview of this information. When focusing on … [Read more...]
Interaction of the system and module-level thermal phenomena- a flip-chip/BGA example
Fig. 1: Levels in a computer environment. Introduction Increasing demands for higher performance in microprocessors have a direct effect on chip power and heat generation. Increased function and miniaturization of the packages result in thermal challenges that require a thorough understanding of the system's thermal performance under all possible field conditions. Regardless … [Read more...]
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